Billionaire Mukesh Ambani's Reliance Industries and U.S. giant Walt Disney are discussing a plan to hold next-stage talks about their India media business merger in London next week, two people familiar with the matter said. Disney and Reliance have held talks to merge their India businesses by forming a joint venture company in which Ambani's media unit would hold a majority stake, though finer details of business structures and valuations are yet to be discussed.